New sampler2D type for the cases when users require a texture reference, but don't care about using a separate sampler state.

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/AbstractMaterialNode.cs

                     return "4x4";
 				case ConcreteSlotValueType.SamplerState:
                     return "SamplerState";
+                case ConcreteSlotValueType.Sampler2D:
+                    return "sampler2D";
                 default:
                     return "Error";
             }
                     return PropertyType.Matrix4;
 				case ConcreteSlotValueType.SamplerState:
                     return PropertyType.SamplerState;
+                case ConcreteSlotValueType.Sampler2D:
+                    return PropertyType.Texture;
                 default:
                     return PropertyType.Vector4;
             }

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/MaterialSlot.cs

                     return "(3x3)";
                 case ConcreteSlotValueType.Matrix4:
                     return "(4x4)";
+                case ConcreteSlotValueType.SamplerState:
+                    return "(SS)";
+                case ConcreteSlotValueType.Texture2D:
+                    return "(T)";
+                case ConcreteSlotValueType.Sampler2D:
+                    return "(S)";
                 default:
                     return "(E)";
             }
                         break;
                     case SlotValueType.SamplerState:
                         concreteValueType = ConcreteSlotValueType.SamplerState;
+                        break;
+                    case SlotValueType.Sampler2D:
+                        concreteValueType = ConcreteSlotValueType.Sampler2D;
                         break;
                     default:
                         concreteValueType = ConcreteSlotValueType.Vector4;

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/SlotValue.cs

     [Serializable]
     public enum SlotValueType
     {
+        Sampler2D,
 		SamplerState,
         Matrix4,
         Matrix3,
 
     public enum ConcreteSlotValueType
     {
+        Sampler2D = 10,
 		SamplerState = 9,
         Matrix4 = 8,
         Matrix3 = 7,